Purpose: Chronic liver disease requires careful follow-up during long-term treatment, and development of a quantitative diagnosis method for liver fibrosis based on an ultrasonic imaging system is highly desired. Methods: Texture analysis using a co-occurrence matrix was applied to both clinical and simulated ultrasonic images of fibrotic livers. A sequence of matrices was generated for pixel-pair distance, r, and texture feature contrast was chosen to examine the response to r in combination with statistical analysis of echo amplitude distribution using a multi-Rayleigh model. Results: The contrast converged with a larger value and fluctuated more significantly in response to r as fibrosis progressed in both the clinical and simulated ultrasonic images. The convergent value rapidly increased at the early stage of fibrosis, and the fluctuation became larger at the advanced stage of fibrosis. Analysis using simulated ultrasonic images with a known fibrous tissue structure theoretically clarified the relationship between contrast behavior and fibrosis progression. Conclusion: It was revealed that contrast convergent value and contrast fluctuation provided information on the fibrous tissue structure, and they are expected to be used for quantitative diagnosis of the degree of liver fibrosis.

Purpose: In the present study, we proposed a novel method for identification of the vascular lumen by employing singular value decomposition (SVD), and the feasibility of the proposed method was validated by in vivo measurement of the common carotid artery. Method: SVD filtering was applied to a velocity map that was estimated using an autocorrelation method to identify the lumen region. In this study, the packet size was set at 999 frames with a frame rate of 1,302 Hz. The region estimated by the proposed SVD filtering was compared with that estimated by the conventional power Doppler method. Result: The averaged differences in feature values between vascular wall and lumen regions obtained by the proposed and conventional methods were 34 dB and 26 dB, respectively. The proposed method was hardly influenced by the cardiac phase and could separate the wall and lumen regions more stably. The proposed method could identify the lumen region by setting a threshold of -28 dB from the averaged difference amplitude. Conclusion: We proposed a novel method for identification of the vascular lumen. The proposed method could suppress the effects of wall motion, which was present in the conventional power Doppler image. The lumen region identified by the proposed method well conformed with the anatomical information in the B-mode image of the corresponding section.

Purpose: From the correlation between the blood flow dynamics and wall dynamics in the left ventriocle (LV) analyzed using echo-dynamography, the ejection mechanisms and role of the intra-ventricular vortex in the LV were elucidated in detail during the pre-ejection transitional period (pre-ETP), the very short period preceding LV ejection. Methods: The study included 10 healthy volunteers. Flow structure was analyzed using echo-dynamography, and LV wall dynamics were measured using both high-frame-rate two-dimensional echocardiography and a phase difference tracking method we developed. Results: A large accelerated vortex occurred at the central basal area of the LV during this period. The main flow axis velocity line of the LV showed a linearly increasing pattern. The slope of the velocity pattern reflected the deformity of the flow route induced by LV contraction during the pre-ETP. The centrifugal force of the vortex at its junction with the main outflow created a stepwise increase of about 50% of the ejection velocity. Conclusion: Ejection of blood from the LV was accomplished by the extruding action of the ventricular wall and the centrifugal force of the accelerated vortex during this period. During ejection, acceralated outflow was considered to create a spiral flow in the aorta with help from the spherical structure of the Valsalva sinus.

Purpose: To assess the feasibility and the clinical usefulness of a newly developed endoscopic ultrasonography (EUS) shearwave elastography technique (EUS shear-wave measurement: EUS-SWM) in the diagnosis and treatment of autoimmune pancreatitis (AIP). Methods: Tissue elasticity was measured in the pancreas in 160 patients. The success rate of EUS-SWMs, the velocity of the shear wave (Vs, m/s), and the reliability index of the Vs measurement (VsN) were evaluated, and the elasticity (median Vs) was compared between AIP patients (n=14) and normal controls. Results: A total of 3837 EUS-SWMs were performed without adverse events. Overall, 97.6% (3,743/3,837) were successful. The median VsN was 74%. The median Vs values of the pancreas were as follows: 2.22 m/s in the pancreatic head (push position), 2.36 m/s in the head (pull position), 1.99 m/s in the body, and 2.25 m/s in the tail. The median Vs of the AIP group (2.57 m/s) was significantly higher than that of the normal controls (1.89 m/s) (P=0.0185). The mean Vs significantly decreased from 3.32 m/s to 2.46 m/s after steroid therapy (n=6) (P=0.0234). Conclusion: EUS-SWM is feasible and generates credible results. EUS-SWM was a useful method for assessment of the effect of steroid therapy in AIP patients.

Purpose: Steatohepatitic hepatocellular carcinoma (SH-HCC) is a newly described subtype of HCC as defined in the 2019 World Health Organization (WHO) classification of tumors. In this study, ultrasound and clinicopathologic studies were conducted on patients who were diagnosed with SH-HCC. SH-HCC has been associated with liver cancer resulting from fatty liver disease; this condition has been identified in an increasing number of patients in recent years. Subjects and Methods: This study included 34 patients in the typical SH-HCC group (7%) and 37 patients in the focal SH-HCC group (8%) out of 477 patients who underwent curative resection of untreated HCC during 2015-2019. We conducted a retrospective clinicopathological study focusing on ultrasound B-mode images. Results and Discussion: The median diameter of the lesions associated with typical SH-HCC was 18 mm. Most of the HCCs were moderately differentiated: 67% exhibited a hyperechoic pattern, 33% presented with a nodule in a nodule pattern, and 83% had a marginal hypoechoic layer. A lateral shadow was detected in 80% of the tumors. Acoustic shadows appeared in 87%. Dynamic computed tomography/magnetic resonance imaging revealed hypervascularity in the arterial phase and washout of contrast medium during the late portal phase; these findings are consistent with normal HCC with fat deposition. By contrast, 69% of those from the focal group presented with findings that were consistent with the ultrasound diagnostic criteria of the Japan Society of Ultrasonics in Medicine for nodules associated with hepatic masses. In both cases, the background liver tissue was notable for advanced fibrosis. Approximately one-third of the background liver tissue included findings consistent with fatty liver; this had a significant impact on B-mode findings or generated difficulties with visualization in the 10% range. Conclusion: Typical SH-HCC showed characteristic B-mode findings, which showed that it is possible to distinguish SH-HCC using ultrasonic images.